<!doctype html>
<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
<div id="div"></div>
<script>
    // document.getElementById('div').onclick = function () {
    //     console.log(this.id)
    //     var func = function () {
    //         console.log(this.id) // 输出div1
    //     }
    //     func.call(this)
    // }
    document.getElementById = (function (func) {
        return function () {
            return func.apply(document, arguments)
        }
    })(document.getElementById)

    let getId = document.getElementById
    console.log(getId('div'));
</script>
</body>
</html>
